1. Scope of Invention
This invention relates generally to pilings and boat lifts supported on pilings and docks, and more particularly to unique boat lift apparatus connectable to, and preferably fully enclosed within an upper portion of a hollow tubular piling.
2. Prior Art
Pilings for supporting a dock and for providing a support and tie-off for boats are typically made of elongated wooden poles, called pilings, for economy. These wooden pilings may be treated in various ways to enhance the useful life thereof.
The following U.S. patents are known to applicant which generally teach the state-of-the-art in conventional pilings for boat lift apparatus as follows:
U.S. Pat. No. 5,772,360 to Wood, II
U.S. Pat. No. 5,839,851 to Norfolk, et al.
U.S. Pat. No. 5,593,247 to Endres, et al.
U.S. Pat. No. 5,378,082 to Hiller, et al.
U.S. Pat. No. 5,628,583 to Gibson
Disclosed within a recent patent by applicant in U.S. Pat. No. 5,934,826 is an improved boat lift apparatus which utilizes inert plastic such as p.v.c to form an upright reinforced tubular piling having significant advantages of economy, longevity and ease of installation over conventional wooden pilings.
The present invention utilizes the advantages of hollow tubular plastic pilings having concrete reinforced lower portions which receive support from the bottom of a body of water by providing an improved boat lift apparatus which is connectable, in its preferred embodiment, within the hollow upper portion of such tubular pilings. The present invention provides full concealment within the hollow tubular piling, while providing superior mechanical advantage through utilization of a unique double worm gear arrangement for force multiplication in lifting, lowering and holding the position of a boat.
This invention is directed to a boat lift apparatus connectable preferably to an elongated tubular piling, a lower portion of the tubular piling receiving support when embedded into a bottom of a body of water. The apparatus includes a motor connected to a gearbox and having an output shaft. A first worm gear arrangement includes a first worm and a first worm gear, the first worm rigidly connected coaxially on the output shaft and drivingly engaged with the first worm gear which is rigidly connected on a first support shaft oriented orthogonally to the output shaft and held for rotation only by the gearbox. An auxiliary thrust bearing is placed between the gearbox and the first worm. A second worm gear set includes a second worm and a second worm gear spaced from the first worm gear set but with the second worm rigidly connected on the first support shaft. The second worm is drivingly engaged with the second worm gear which is rigidly connected on a second support shaft oriented orthogonally to the first support shaft and held for rotation only by the gearbox. A preferred feature is a thrust member positioned on the motor output shaft which transfers one-directional thrust to the motor housing. The invention may also include one or more cable drums having lengths of wrapped cable that may be mounted for rotation on additional support shafts connected to an elongated frame and oriented substantially parallel to the second support shaft, the frame being connected to the gearbox. The cable drums are operably connected to, and rotationally driven from, the second support shaft responsive to rotational output of the output shaft to withdraw and extend the cable on the cable drum.
It is therefore an object of this invention to provide a boat lift apparatus having no visible portion thereof such as a motor, gearbox, cables or controls, all of which are concealed within a hollow tubular piling.
It is another object of this invention to provide a boat lift apparatus with significantly superior weight-lifting capabilities over those conventional prior art apparatus of a similar overall size, weight and cost.
It is still another object of this invention to provide a boat lift mechanism which is self-locking and will not back drift or spool outwardly when power to the motor is removed.
It is yet another object of this invention to provide a boat lift apparatus which may be connectable atop an existing conventional piling without the need for piling replacement.
Still another object of this invention is to provide a boat lift apparatus which is connectable onto an existing dock or overhead boat lift structure without the need for modification thereof.
Another object of this invention is to provide a portable boat lift apparatus which is operable by the utilization of a separate battery-powered drill or other rotary output device.
It is still another object of this invention to provide a uniquely structured cable drum for use in conjunction with a boat lift apparatus which provides superior cable winding features and cable longevity.
A yet further object is the transfer of worm/worm gear one-directional thrust directly to the motor housing so as to preserve the integrity of the motor bearings which are not typically designed to absorb axial thrust.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with reference to the accompanying drawings.